1. Field of the Invention
This invention relates to a switching mechanism such as a heating-cooling mode switching valve in a heating-cooling apparatus, namely, an air-conditioning apparatus, and more particularly to a rotation switching mechanism in a rotary type switching valve in which a movable switching valve consists of a rotor.
2. Brief Description of the Prior Art
Heretofore, there have been known a sliding type switching valve and a rotary type switching valve to serve as a cooling-heating mode switching valve in a heating-cooling apparatus. In the rotary type switching valve, a means for driving a rotor to serve as the movable valve comprises an electromagnet having a return spring. Sliding of the slider in one direction caused by supplying electric current to the electromagnet and sliding of the slider in the other direction caused by the spring, cause the rotor to be rotated by a predetermined angle.
However, the above conventional switching mechanism has shortcomings in that, when the spring becomes fatigued, the stroke of the slider caused by the spring is not uniform with the stroke of the slider caused by supply of electric current, and as a result, a predetermined angle of rotation of the rotor and the switching valve are not reliable.
Moreover, due to play of a connecting portion between the slider and the rotor, the above-mentioned non-uniformity is increased. In addition, since the slider is required to be slid normally in one direction against the load of the spring, the force of the electromagnet is not efficiently transmitted to the rotor and, as a result, provision of an electromagnet having a large capacity is required.
The present invention has been accomplished in view of the above situation.